JPH10160601A - Pressure detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine the height of fluidized bed accurately by blowing gas into a fluidized bed furnace and measuring the back pressure thereof so that the inner pressure of the fludized bed furnace can be measured accurately thereby detecting the differential pressure accurately. SOLUTION: Refuse and silica sand are fed through a refuse/fluid medium supply pipe 2 into a fluidized bed furnace while the air is blown out through an air introduction pipe 5 and combustible refuse is burnt. Furthermore, compressed air is blown out through air jet pipes 6, 16. Consequently, back pressure of same level as the jetting pressure of compressed air is generated in back pressure detection pipes 9, 19. Inner pressure at the forward end of the jet pipes 16 can be detected by means of a pressure gauge 23. Differential back pressure between the back pressure detection pipes 9, 19 represents the pressure difference between upper and lower positions which is proportional to the height of fluidized bed. Consequently, the height of fluidized bed can be determined by measuring the differential back pressure between the back pressure detection pipes 9, 19 with differential pressure gage 10 and performing a theoretical calculation based on the differential pressure through an appropriate arithmetic unit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure detecting method for detecting an internal pressure at a predetermined location in a fluidized bed furnace and a differential pressure between two locations.

[0002]

2. Description of the Related Art In a fluidized bed furnace, it is necessary to form a stable fluidized bed for stable combustion or thermal decomposition. In the case of having a heat exchanger at the place where the fluidized bed is formed, a fixed fluidized bed height is set to prevent the fluidized bed height from being too high or too low and causing the heat exchange amount to be disturbed. It is important to keep. In addition, it is important to keep the change in the height of the fluidized bed due to the change in the amount of incombustibles contained in the refuse or the scattering of the fluid medium to a minimum. Therefore, it is necessary to detect an accurate fluidized bed height.

[0003] The fluidized bed height can be obtained by measuring the internal pressure at two locations above and below the fluidized bed furnace and theoretically calculating the pressure difference between the two locations. Conventionally, one end of a pressure detection tube is connected to each of two upper and lower locations in a fluidized bed furnace, and the other end of both pressure detection tubes is connected to a differential pressure gauge to obtain a differential pressure between two locations in the furnace. The height of the fluidized bed is obtained from the differential pressure by theoretical calculation (see Japanese Patent Application Laid-Open No. 1-268813).

[0004]

Since a fluidized medium (silica sand, etc.) and dust are present in the fluidized-bed furnace, the internal pressure at a predetermined location of the fluidized-bed furnace or two places is determined by the pressure detection tube as described above. In the case of detecting the pressure difference between them, there is a problem that the flowing medium or dust may enter the pressure detection tube, and it is not possible to detect the internal pressure accurately.

[0005] Further, since it is impossible to detect an accurate internal pressure, an accurate differential pressure cannot be detected, and as a result, there is a problem that an accurate fluidized bed height cannot be obtained.

[0006] An object of the present invention is to solve the above-mentioned problems and to detect an accurate internal pressure at each point in a fluidized bed furnace.
As a result, it is an object of the present invention to provide a pressure detection method capable of detecting an accurate differential pressure between two locations and obtaining an accurate fluidized bed height.

[0007]

A pressure detecting method according to the present invention detects an internal pressure of a fluidized-bed furnace by blowing a constant mass of gas into a fluidized-bed furnace and measuring a back pressure of the injection pressure at which the gas is blown. Therefore, it is possible to detect an accurate internal pressure without the fluid medium or the like in the furnace entering the injection pipe that blows the gas.

In some cases, a gas having a constant mass is blown into two upper and lower locations in a fluidized-bed furnace, and a differential pressure in the fluidized-bed furnace is detected based on a difference between back pressures of injection pressures at which the gas is blown at the two upper and lower locations. . In this case, since an accurate differential pressure between the two locations can be detected, an accurate fluidized bed height can be obtained by theoretical calculation. It is desirable that the air blowing direction be the same. This is for detecting an accurate differential pressure.

The use of air as the gas to be blown does not affect the combustion in the fluidized-bed furnace.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of a refuse incinerator equipped with a fluidized bed furnace capable of determining a fluidized bed height by the method of the present invention.

A refuse / fluid medium supply pipe (2) is connected to the fluidized bed furnace (1) at substantially the center of its height, and an exhaust gas outlet pipe (3) is connected to the upper part of the fluidized bed furnace (1). At the same time, a combustion air inlet pipe (5) is arranged at the bottom of the fluidized bed furnace (1), and air is blown upward from the air inlet pipe (5), The refuse and the fluidized medium are made into a fluidized bed, and the refuse is burned. Fluid bed furnace
An opening (4) is formed at the lower end of (1).

Air injection pipes (6) and (16) are provided in the upper and lower portions of the fluidized bed furnace (1) through one side wall of the fluidized bed furnace (1). Nozzles (not shown) are provided at the ends of the air injection pipes (6) and (16) in the fluidized bed furnace (1). One ends of compressed air supply pipes (7) and (17) are connected to ends of air injection pipes (6) and (16) located outside the fluidized bed furnace (1), respectively. In the middle of the compressed air supply pipes (7) and (17), flow control valves (8) and (18) are provided, respectively.

Although not shown, the other ends of the compressed air supply pipes (7) and (17) are connected to a suitable compressed air supply device such as a compressor. The pressure and temperature of the compressed air supplied to each of the air injection pipes (6) and (16) by the compressed air supply device are kept constant and the same value. In addition, a fluidized bed furnace (1)
At the end located outside the back pressure detection tube (9) (19)
Is connected. The back pressure detecting pipes (9) and (19) are connected to a differential pressure gauge (10) through chambers (11) and (21), respectively.
Further, the lower back pressure detection pipe (19) is connected to a pressure gauge (23) via a chamber (22).

In the above refuse incinerator, refuse and silica sand (fluidized medium) are supplied from the refuse / fluidized medium supply pipe (2) into the fluidized bed furnace (1) as needed, and
Air is blown upward from the air introduction pipe (5) in (1), forming a fluidized bed of garbage and silica sand in the fluidized bed furnace (1), and combustible garbage is burned .

The silica sand and the non-combustible waste are discharged from the lower opening (4) of the fluidized-bed furnace (1). Although not shown, the discharged non-combustible waste is separated from silica sand by a suitable separation device, and only the silica sand is re-supplied together with the waste from the waste / fluid medium supply pipe (2). Silica sand is circulated through a circulation path consisting of a fluidized bed furnace (1) and a waste / fluid medium supply pipe (2).

During the initial charging of dust and the like into the fluidized bed furnace (1) and during the normal operation of the fluidized bed furnace (1), compressed air is supplied from the air injection pipes (6) and (16) in the fluidized bed furnace (1) respectively. Is blown upward. At this time, since the temperature and pressure of the compressed air supplied to the air injection pipes (6) and (16) by the compressed air supply device are kept constant as described above, the air injection pipe
(6) The volume of compressed air supplied to (16) is
If the pressure is kept constant by (8) and (18), the mass of the compressed air blown into the fluidized bed furnace (1) can be kept constant.

The back pressure detecting tubes (9) and (19) include an air injection tube (6).
The back pressure of the same value as the injection pressure injected into the fluidized bed furnace (1) by injecting compressed air from (16) is generated. Since the lower back pressure detecting pipe (19) is connected to the pressure gauge (23), the pressure gauge (2
The difference between the back pressure and the atmospheric pressure generated in the lower back pressure detection pipe (19) due to 3), that is, the lower air injection pipe in the fluidized bed furnace (1)
The internal pressure at the position where the tip of (16) is located can be detected.

The back pressure difference between the back pressure detecting pipes (9) and (19) is the pressure difference between the upper and lower portions in the fluidized bed furnace, and the difference between the two locations in the fluidized bed furnace (1). Pressure difference and fluidized bed height are proportional, so a differential pressure gauge (10)
The height of the fluidized bed can be determined by measuring the difference in back pressure generated in (19) and performing theoretical calculation based on the differential pressure by a suitable arithmetic unit. The minute pressure fluctuation and the temporary pressure fluctuation are absorbed by the chambers (11), (21) and (22).

As described above, the internal pressure of the fluidized-bed furnace (1) and the fluidized-bed height can be immediately known, so that even when the refuse is initially charged or during normal operation,
The internal pressure and the height of the fluidized bed can be easily confirmed from the outside.

Further, the differential pressure gauge (10) and the pressure gauge (23) are visually checked, and the amount of the refuse or the flowing medium to be supplied is manually adjusted, or the differential pressure gauge (10) and the pressure gauge (23) Is connected to an appropriate control device to automatically adjust the amount of refuse or fluid medium to be supplied based on the differential pressure and the internal pressure, and to maintain the internal pressure and the differential pressure at predetermined values to stabilize combustion. It can be carried out.

Note that the application of the pressure detection method of the present invention is not limited to the refuse incinerator of the above embodiment, but can also be applied to a pyrolysis apparatus using a fluidized bed furnace, a smelting reduction furnace, or the like. .

[0023]

According to the pressure detecting method of the present invention, a predetermined mass of gas is blown into a fluidized-bed furnace, and the back pressure of the injection pressure at which the gas is blown is measured. Because it detects the pressure difference between the furnace, it is possible to accurately detect the internal pressure or the pressure difference without the fluid medium in the furnace entering the injection pipe that blows the gas, and based on the detected pressure difference By performing the calculation, an accurate fluidized bed height can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a refuse incinerator showing one embodiment of the present invention.

[Explanation of symbols]

 (1) Fluidized bed furnace

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Tomohiro Aoki 5-3-28 Nishikujo, Konohana-ku, Osaka-shi Inside Hitachi Zosen Corporation (72) Inventor Takeshi Ken Matsui 5-28-3, Nishikujo, Konohana-ku, Osaka-shi Within Hitachi Zosen Corporation (72) Inventor Morio Sugiura 5-28 Nishikujo, Konohana-ku, Osaka Hitachi Zosen Corporation

Claims (3)

[Claims] 1. A pressure detecting method for detecting the internal pressure of a fluidized-bed furnace by blowing a constant mass of gas into the fluidized-bed furnace and measuring the back pressure of the injection pressure for blowing the gas. 2. A pressure detecting method for blowing a gas having a constant mass into upper and lower portions of a fluidized-bed furnace, and detecting a differential pressure in the fluidized-bed furnace based on a difference between back pressures of injection pressures at which the gas is blown at the upper and lower portions. . 3. The pressure detecting method according to claim 1, wherein the gas to be blown is air.